Step by step recipe:

1. 5 min.

   Prepare the pissaladière topping

   Remove the stones from 50 g black olives, then chop roughly.
   
   Set aside.
2. 5 min.
   Prepare 200 g onion, but slice thinly. A mandolin is the most effective tool for this.
3. 3 min.
   Heat 4 tablespoons olive oil in a saucepan on medium heat.
   
   When really hot, add the onion, salt and pepper, then mix well.
4. 10 min.
   Turn down the heat and leave to cook for 10 minutes or so, stirring regularly and without colouring.
5. 3 min.
   Add the chopped olives, mix well and cook for a further 3 minutes.
6. 2 min.
   Add 250 g peeled tomatoes, 20 g tomato paste and 1 Bouquet garni.
7. 30 min.
   Leave uncovered on low heat to cook for about 30 minutes. The mixture should stew down to the consistency of a "compote" or thick sauce.
8. 
   Finish by adding the chopped parsley, take off the heat and check the seasoning. Leave to cool.
9. 3 min.

   Fill and cook the pissaladière

   Preheat the oven to 370°F (190°C).
   
   Roll out 200 g Puff or flaky pastry (pâte feuilletée) into a large circle and put on a baking sheet on a sheet of cooking parchment (the pastry may have come with one).
   
   Prick the pastry all over.
10. 4 min.
    Spread a generous layer of topping over the pastry base.
11. 3 min.
    Finish by arranging 30 g anchovy fillets on top and scatter a little oregano over.
12. 30 min.
    Bake for 30 minutes.
    
    Serve either warm or cold.